Valve control mechanism for hydraulic classifiers



Dec. 28, 1948. R. o. STOKES 2,457,412

VALVE CQNTROL MECHANISM FOR HYDRAULIC CLASSIFIERS Filed Oct. 16, 1945 :s 'sn ets-sheet 1 Dec. 28, .1948.

Filed Oct. 16, 1945 I I I l I R. O. STOKES VALVE CONTROL MECHANISM FOR HYDRAULIC CLASSIFIERS 3 S heets-Sheet 2 Dec. 28, 1948. TOKE 2,457,412

. VALVE common MECHANISM FOR HYDRAULIC CLASSIFIERS Fi' led Oct. 1a, 1945 I s She'ets-Sheet s Patented Dec. 28, 1948 UNITED STATES PATENT OFFICE VALVE CONTROL MECHANISM FOR HYDRAULIC CLASSIFIERS ;Rupe rt Octavius Stokes, London, England Application October 16, 1945, Serial No. 622,629

- In Great Britain October 24, 1944 1 Claim. (Cl. 209'496) The invention relates to valve control mechanism for hydraulic classifiers and has been devised primarily as a modification of the hydrosizer disclosed in the specification of British patent No. 509,020, and corresponding United States patent 2,219,639, issued Oct. 29, 1940. In that specification a hydraulic classifier of the hindered settling type was provided with a valve for the continuous discharge of the larger or heavier solids, and an arrangement provided for adjustin the degree of opening of the valve in dependence on the effective head of the column of teetering solids comprised means such as a diaphragm chamber sensitive to changes in the said effective head and a hydraulic transmission to adjust the valve in dependence on the diaphragm movements. The invention is also applicable to such apparatus as thickeners which are in effect hydraulic classifiers working under free settling conditions.

According to the present invention in a classifier of the kind referred to the discharge valve is adjusted as to degree of opening by an improved reversible electric motor having its circuit controlled by a reversing switch, and the reversing switch is actuated in response to the relative movement of elements dependent in position on the degree of opening of the discharge valve and on the effective head of the teetering or settled solids respectively.

It is most convenient to mount the reversing switch on a carrier coupled by lever to the discharge valve and to couple the operating lever of the switch to a diaphragm subjected to the effective head of the teetering or settled solids.

The valve control mechanism of the present invention is simpler than the hydraulic mechanism of the prior patent and is of particular advantage where there is no clean water supply at a constant head for the hydraulic chamber having constricted channels connecting it to the supply and discharge. On the other hand there will still be cases where the hydraulic operation of the prior patent is preferable to the present invention.

The invention is illustrated by an embodiment shown in the accompanying drawings, in which Figure 1 is an elevation of the valve control mechanism,

Figure 2 is a side elevation in section of the motor, switch and associated parts on a larger scale,

Figure 3 is an end elevation of the same, and

Figure 4 is a plan of the switch on a larger scale still.

Referring firstto Figure 1, the discharge valve is adjusted as to degree of opening by a lever l pivoted by a link 2 on a casing 3, which is mounted on the hydrosizer to contain the electrical apparatus. The right hand end of the lever I is shown in its lowest position and is provided with an arrangement for hand operation of the valve comprising a handle 4 and spring5. A diaphragm chamber 6 is subjected'to a pressure dependent on the head of teetering solids as disclosed in the prior specification mentioned above, and the movements of the diaphragmare communicated to the switch to be described later by a rod 1.

Referring now to Figures 2 and 3, a cradle 8 has the end of the lever I pivoted to it and is fixed to vertical rods 9, 9, which slide in guides l0 and II in the casing 3. The rods 9, 9 are fastened together further by a cross bar 12 and a switch base Hi. The cross bar I2 has a tapped hole at the centre to engage a vertical screwed shaft l4 journalled in the casing 3. The shaft I4 is driven through worm gear I5 from a small capacitor motor I6, of which the condenser is shown at IT.

The rod 1 has a head l8 fixed to it for operating the switch shown in Figures 2, 3 and 4. A lever H! of insulating fibre is pivoted by a pin 29 in the base l3 and is coupled by a pin-2| to the head I8. A metal bushing 20 in the fibre lever l9 provides a bearing for the pin 20. Contact strips 22 and 23 of brass are fixed by means of terminals 24 and 25 to the lever I 9, each terminal being electrically connected to one strip and insulated from the other.

Two brass strips 26, 26 are pivoted by a pin 21 in the base [3 and are also coupled by the pin 2| to the head l8. The strips 26, 26 have clearance holes for the pin 20. Fibre blocks 28, 28 attached to the strips 26, 26 carry a brass contact bar 29, on a projecting end of which there is a terminal 30. It will be seen that, when the rod rises, the contact bar 29 also rises and the contact strips 22 and 23 are lowered, and the reverse when the rod 1 falls. The effect is that, with the dimensions shown, a given relative movement between the rod 1 and the switch bar l3 gives rise to a relative movement 5 /2 times as large between the contact strips 22 and 23 and the contact bar 29.

In normal steady operation the contact bar 29 is floating between the contact strips 22 and 23 and the motor I6 is at rest. If a change takes place in the feed of material which increases the apparent density of the teeterin column, the pressure in the diaphragm chamber 6 is increased and the diaphragm moves against spring pressure, raising the rod 1 and so lifting the contact bar 29 and lowering the contact strip 22. The motor circuit is completed and the motor runs in a direction to open the discharge valve. At the same time the switch base 13 is raised and carries the switch up to a new equilibrium position, breaking the motor circuit. If the apparent density of the teetering column falls, similar action takes place in the reverse direction.

What I claim is:

In equipment for classifying the solid and liquid constituents of a mixture, of the class wherein a valve operable by a reversible electric motor controls the discharge of solids accumulating ina bed under the conjoint control of the positioning of the valve itself and operation of a pressure actuated device responsive to pressure in said equipment, the combination with said motor and said pressure actuated device of a reversing switch comprising a switch base, a first lever pivoted on the base, upper and lower contacts on the said first lever,-a second lever pivoted on the base, the lever pivots being spaced apart in the length direction of the levers, a contactmember mounted on the said second lever to make contact selectively with the upper and lower contacts on the first lever and normally to float between the said contacts, a connection from the pressure actuated device to the two levers acting at a position between their respective pivots to move the levers in contrary directions on a movement of the pressure actuated device, electrical connections between the switch and the motor to cause the REFERENCES CITED 'Ihe iollowing references are of record in the file of this patent:

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